1. Technical Field
The present invention relates generally to safety clamps attached to a user that come into gripping engagement with a safety line if the user falls. More particularly, the safety clamp attaches to a belt worn by the user, and incorporates a friction plate or shoe that is moved into gripping engagement with safety line adjacent the user's location, as for example on a ladder.
2. Background Information
Safety clamps of the type herein described have been known and used for many years. Similar devices are disclosed in U.S. Pat. No. 4,071,926, issued to Sweet et al. on Feb. 7, 1978, and U.S. Pat. No. Re. 30,072, originally issued to Kleine et al. as U.S. Pat. No. 3,908,791 on Sept. 30, 1975. A primary problem of prior safety clamps has been the need to use two hands to attach and remove the safety clamp to and from the safety line. Depending on the position of the worker at the time, this operation can be difficult at best, if not quite dangerous. Further, these devices are intended to permit easy ascent of the worker along a ladder or similar climbing device, while quickly engaging the safety line if the user suddenly falls. However, if the device is inadvertently installed in an upside down configuration, the user will have a difficult time climbing, and will receive no protection in the event of a fall.
Additionally, prior safety clamps frequently relied on the contact between the end of a cam arm and the safety line to provide the grasping action that stopped the fall of the worker. This was often the case even though a more secure grasping action is known to be had by using a larger surface are for contacting the safety line, such as may be obtained from a brake shoe, for example. Other devices have been developed that utilize a larger plate or shoe, but these have the accompanying problem of keeping the shoe properly aligned with the safety cable to maximize the surface area of the shoe in contact with the safety cable.
Another problem that can occur when using prior safety clamps is that they are frequently built to be used with cable of a specific diameter or close range of diameters However, there is not always a way of keeping the device from being used with a cable of a different size. In the event that this should occur, the performance of the safety clamp may be detrimentally affected, increasing the risk of failure of the safety clamp in the event the worker should fall.
The ladder climbing safety clamp of the present invention overcomes the difficulties described above and affords other features and advantages heretofore not available.